The present invention relates to a navigation system mounted on a mobile, e.g., an automobile and a vehicle. More specifically, the present invention is directed to a mobile navigation system capable of judging an end of a traffic jam until an automobile approaches such place.
A mobile navigation system is widely utilized in the field. For instance, one conventional mobile navigation system is described in Japanese Unexamined Patent Publication 6-180796, the schematic system diagram of which is shown in FIG. 1. In this drawing, reference numeral 1 indicates the map data storage unit for storing the map data, reference numeral 2 represents the GPS (Global Positioning System) receiver unit arranged by the GPS system, for detecting a present position of a vehicle (not shown in detail), and reference numeral 3 shows the traffic information receiving unit for receiving the transmitted traffic information.
Also, reference numeral 4 indicates the navigation unit for calculating the present position of the vehicle based upon the signal outputted from the GPS receiver unit 2, and for entering therein this present position information and the map data stored in the map data storage unit 1 to thereby search a route from this present position to a target (destination) position. Reference numeral 5 shows the system control unit for controlling an information display by the display unit 6 in response to the outputs derived from the navigation unit 4 and the traffic information receiving unit 3. The display unit 6 is constructed of the LCD (liquid crystal display). Reference numeral 7 is the voice unit for producing alarm sound.
Subsequently, the operations of this conventional mobile navigation system will now be explained.
First, the navigation unit 4 searches the optimum route defined from the present position up to the destination place, and the road information receiving unit 3 receives the traffic jam information.
Then, the system control unit 5 judges as to whether or not a region indicative of the above-described traffic jam information is contained in the route. If the system control unit 5 judges that the region indicative of the traffic jam is not contained in the route, then this route is displayed on the display unit 6. Conversely, if the system control unit 5 judges that the traffic-jam region is contained in the route, then the navigation unit 4 is brought into the standby state in order to re-search the route, and furthermore the voice unit 7 is actuated, so that the operator is requested to judge as to whether or not the route is again searched.
As described above, since the conventional mobile navigation system is so arranged, this navigation system never considers such a case that the traffic jam will be solved until the moving object reaches this traffic jam region. As a consequence, there is a problem that the operator must judge as to whether or not the route is required to be again searched under the following initial condition. That is, the traffic jam region is still present in the route even in the above-explained case.